import { describe, expect, it } from "vitest";
import {
  SCHEMA_LIMITS,
  compareSchemas,
  generateSample,
  inspectWorkspace,
  parseSchemaDocument,
  validateJsonInstance,
} from "../../src/schema/model";

const entry = {
  name: "person.schema.json",
  language: "json-schema" as const,
  source: JSON.stringify({
    $schema: "https://json-schema.org/draft/2020-12/schema",
    type: "object",
    required: ["name", "address"],
    properties: {
      name: { type: "string", minLength: 1 },
      address: { $ref: "defs/address.json#/$defs/address" },
    },
    additionalProperties: false,
  }),
};
const support = {
  name: "defs/address.json",
  language: "json-schema" as const,
  source: JSON.stringify({
    $schema: "https://json-schema.org/draft/2020-12/schema",
    $defs: {
      address: {
        type: "object",
        required: ["city"],
        properties: { city: { type: "string" } },
      },
    },
  }),
};

function nestedJsonSchema(levels: number): object {
  let schema: object = { const: "leaf" };
  for (let level = 1; level < levels; level += 1)
    schema = {
      type: "object",
      required: ["child"],
      properties: { child: schema },
    };
  return schema;
}

function jsonValueDepth(value: unknown): number {
  if (!value || typeof value !== "object") return 1;
  const children = Object.values(value);
  return 1 + (children.length ? Math.max(...children.map(jsonValueDepth)) : 0);
}

function xsdChain(levels: number): string {
  const types = Array.from({ length: levels - 1 }, (_, index) => {
    const number = index + 1;
    const childType = number === levels - 1 ? "xs:string" : `Type${number + 1}`;
    return `<xs:complexType name="Type${number}"><xs:sequence><xs:element name="level${number + 1}" type="${childType}"/></xs:sequence></xs:complexType>`;
  }).join("");
  return `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">${types}<xs:element name="level1" type="Type1"/></xs:schema>`;
}

function relaxNgChain(levels: number): string {
  let pattern = "<text/>";
  for (let level = levels; level >= 1; level -= 1)
    pattern = `<element name="level${level}"><group>${pattern}</group></element>`;
  return `<grammar xmlns="http://relaxng.org/ns/structure/1.0"><start>${pattern}</start></grammar>`;
}

function hasUnpairedSurrogate(value: string): boolean {
  for (let index = 0; index < value.length; index += 1) {
    const code = value.charCodeAt(index);
    if (code >= 0xd800 && code <= 0xdbff) {
      const next = value.charCodeAt(index + 1);
      if (next < 0xdc00 || next > 0xdfff) return true;
      index += 1;
    } else if (code >= 0xdc00 && code <= 0xdfff) return true;
  }
  return false;
}

const amplifiedChoiceSupport = {
  name: "choices.json",
  source: JSON.stringify({
    $defs: {
      impossible: {
        anyOf: Array.from({ length: 600 }, () => false),
      },
      amplified: {
        anyOf: Array.from({ length: 100 }, () => ({
          $ref: "#/$defs/impossible",
        })),
      },
    },
  }),
};

function captureError(run: () => unknown): Error {
  try {
    run();
  } catch (error) {
    if (error instanceof Error) return error;
    throw error;
  }
  throw new Error("Expected operation to throw.");
}

describe("schema workspace", () => {
  it("resolves local references, generates a sample, and validates instances", () => {
    const workspace = inspectWorkspace([entry, support], entry.name);
    expect(workspace.references).toEqual([
      expect.objectContaining({ target: support.name, status: "resolved" }),
    ]);
    expect(JSON.parse(generateSample(workspace).output)).toEqual({
      name: "string",
      address: { city: "string" },
    });
    expect(
      validateJsonInstance(
        workspace,
        JSON.stringify({ name: "Ada", address: { city: "London" } }),
      ).valid,
    ).toBe(true);
    const invalid = validateJsonInstance(
      workspace,
      JSON.stringify({ name: "Ada" }),
    );
    expect(invalid.valid).toBe(false);
    expect(invalid.diagnostics[0]?.message).toContain("required");
  });

  it("bounds repeated large literal samples reached through local references", () => {
    const properties = Object.fromEntries(
      Array.from({ length: 100 }, (_, index) => [
        `value${index}`,
        { $ref: "literal.json#/$defs/large" },
      ]),
    );
    const workspace = inspectWorkspace([
      {
        name: "root.json",
        source: JSON.stringify({
          type: "object",
          required: Object.keys(properties),
          properties,
        }),
      },
      {
        name: "literal.json",
        source: JSON.stringify({
          $defs: { large: { default: "x".repeat(100_000) } },
        }),
      },
    ]);

    const sample = generateSample(workspace);
    const values = Object.values(JSON.parse(sample.output) as object);
    expect(sample.output.length).toBeLessThanOrEqual(
      SCHEMA_LIMITS.sampleOutputChars,
    );
    expect(values).toHaveLength(100);
    expect(
      values.every(
        (value) => String(value).length <= SCHEMA_LIMITS.sampleValueChars,
      ),
    ).toBe(true);
    expect(sample.notices.join("\n")).toMatch(/truncated.*safety bound/iu);
  });

  it("applies the exact JSON node budget to copied literal collections", () => {
    const workspace = inspectWorkspace([
      {
        name: "literal-array.json",
        source: JSON.stringify({
          default: Array.from({ length: 100 }, () =>
            Array.from({ length: 20 }, () => null),
          ),
        }),
      },
    ]);
    const sample = generateSample(workspace);
    const value = JSON.parse(sample.output) as unknown;
    const countNodes = (item: unknown): number =>
      item && typeof item === "object"
        ? 1 +
          Object.values(item).reduce((sum, child) => sum + countNodes(child), 0)
        : 1;
    expect(countNodes(value)).toBe(SCHEMA_LIMITS.sampleNodes);
    expect(sample.notices.join("\n")).toMatch(/node.*safety bound/iu);
  });

  it("monotonically bounds amplified JSON choice attempts through reused refs", () => {
    const properties = Object.fromEntries(
      Array.from({ length: 100 }, (_, index) => [
        `value${index}`,
        { $ref: "choices.json#/$defs/value" },
      ]),
    );
    const workspace = inspectWorkspace([
      {
        name: "root.json",
        source: JSON.stringify({
          type: "object",
          required: Object.keys(properties),
          properties,
        }),
      },
      {
        name: "choices.json",
        source: JSON.stringify({
          $defs: {
            value: {
              anyOf: [
                ...Array.from({ length: 600 }, () => false),
                { const: "viable" },
              ],
            },
          },
        }),
      },
    ]);

    const started = performance.now();
    const error = captureError(() => generateSample(workspace));
    const elapsed = performance.now() - started;
    expect(error.message).toMatch(/sample budget was exhausted/iu);
    expect(error.message).not.toMatch(/first viable/iu);
    expect(elapsed).toBeLessThan(2_000);
  });

  it("never treats exhausted all-impossible anyOf or oneOf branches as viable", () => {
    for (const keyword of ["anyOf", "oneOf"] as const) {
      const workspace = inspectWorkspace([
        {
          name: `${keyword}.json`,
          source: JSON.stringify({
            [keyword]: Array.from({ length: 100 }, () => ({
              $ref: "choices.json#/$defs/impossible",
            })),
          }),
        },
        amplifiedChoiceSupport,
      ]);

      const error = captureError(() => generateSample(workspace));
      expect(error.message).toMatch(/sample budget was exhausted/iu);
      expect(error.message).not.toMatch(/first viable/iu);
    }
  });

  it("refuses a partial mandatory allOf when prior work exhausts the budget", () => {
    const properties = Object.fromEntries(
      Array.from({ length: 100 }, (_, index) => [
        `value${index}`,
        { $ref: "choices.json#/$defs/amplified" },
      ]),
    );
    const workspace = inspectWorkspace([
      {
        name: "all-of.json",
        source: JSON.stringify({
          allOf: [
            {
              type: "object",
              required: Object.keys(properties),
              properties,
            },
            false,
          ],
        }),
      },
      amplifiedChoiceSupport,
    ]);

    expect(() => generateSample(workspace)).toThrow(
      /sample budget was exhausted/iu,
    );
  });

  it("propagates optional-property exhaustion before later required constraints", () => {
    for (const requiredSchema of [{ const: "required" }, false] as const) {
      const workspace = inspectWorkspace([
        {
          name: "optional-before-required.json",
          source: JSON.stringify({
            type: "object",
            required: ["required"],
            properties: {
              optional: { $ref: "choices.json#/$defs/amplified" },
              required: requiredSchema,
            },
          }),
        },
        amplifiedChoiceSupport,
      ]);

      expect(() => generateSample(workspace)).toThrow(
        /sample budget was exhausted/iu,
      );
    }
  });

  it("propagates work exhaustion from a required array item", () => {
    const workspace = inspectWorkspace([
      {
        name: "required-item.json",
        source: JSON.stringify({
          type: "array",
          minItems: 1,
          items: { $ref: "choices.json#/$defs/amplified" },
        }),
      },
      amplifiedChoiceSupport,
    ]);

    expect(() => generateSample(workspace)).toThrow(
      /sample budget was exhausted/iu,
    );
  });

  it("charges cached wide JSON property visits on every reused schema", () => {
    const wideProperties = Object.fromEntries(
      Array.from({ length: 2_000 }, (_, index) => [
        `optional${index}`,
        { type: "string" },
      ]),
    );
    const workspace = inspectWorkspace([
      {
        name: "wide-references.json",
        source: JSON.stringify({
          allOf: Array.from({ length: 2_000 }, () => ({
            $ref: "wide.json#/$defs/wide",
          })),
        }),
      },
      {
        name: "wide.json",
        source: JSON.stringify({
          $defs: {
            wide: { type: "object", properties: wideProperties },
          },
        }),
      },
    ]);

    const started = performance.now();
    const error = captureError(() => generateSample(workspace));
    expect(error.message).toMatch(/sample budget was exhausted/iu);
    expect(performance.now() - started).toBeLessThan(2_000);
  });

  it("admits exactly 20 generated JSON levels and omits level 21", () => {
    const exact = inspectWorkspace([
      {
        name: "depth-20.json",
        source: JSON.stringify(nestedJsonSchema(20)),
      },
    ]);
    const exactSample = generateSample(exact);
    expect(jsonValueDepth(JSON.parse(exactSample.output))).toBe(20);
    expect(exactSample.notices.join("\n")).not.toMatch(/level safety bound/iu);

    const excessive = inspectWorkspace([
      {
        name: "depth-21.json",
        source: JSON.stringify(nestedJsonSchema(21)),
      },
    ]);
    const boundedSample = generateSample(excessive);
    expect(jsonValueDepth(JSON.parse(boundedSample.output))).toBe(20);
    expect(boundedSample.notices.join("\n")).toMatch(/level safety bound/iu);
  });

  it("truncates JSON literals without splitting surrogate pairs", () => {
    const value = `a${"😀".repeat(600)}`;
    const workspace = inspectWorkspace([
      {
        name: "unicode.json",
        source: JSON.stringify({ default: value }),
      },
    ]);
    const generated = JSON.parse(generateSample(workspace).output) as string;
    expect(generated.length).toBeLessThanOrEqual(
      SCHEMA_LIMITS.sampleValueChars,
    );
    expect(hasUnpairedSurrogate(generated)).toBe(false);
  });

  it("refuses to claim a sample for the always-invalid false schema", () => {
    const workspace = inspectWorkspace([
      { name: "impossible.json", source: "false" },
    ]);
    expect(() => generateSample(workspace)).toThrow(/no valid sample/iu);
  });

  it("refuses false schemas reached through references and required combiners", () => {
    const referenced = inspectWorkspace([
      { name: "root.json", source: JSON.stringify({ $ref: "defs.json" }) },
      { name: "defs.json", source: "false" },
    ]);
    expect(() => generateSample(referenced)).toThrow(/no valid sample/iu);

    const combined = inspectWorkspace([
      {
        name: "combined.json",
        source: JSON.stringify({ allOf: [{ type: "object" }, false] }),
      },
    ]);
    expect(() => generateSample(combined)).toThrow(/no valid sample/iu);
  });

  it("skips impossible alternatives when a viable anyOf sample exists", () => {
    const workspace = inspectWorkspace([
      {
        name: "choice.json",
        source: JSON.stringify({
          anyOf: [false, { type: "string", const: "viable" }],
        }),
      },
    ]);
    expect(JSON.parse(generateSample(workspace).output)).toBe("viable");
  });

  it("blocks remote and missing references without attempting resolution", () => {
    const workspace = inspectWorkspace([
      {
        name: "unsafe.json",
        source: JSON.stringify({ $ref: "https://example.test/schema.json" }),
      },
      { name: "missing.json", source: JSON.stringify({ $ref: "other.json" }) },
    ]);
    expect(workspace.references.map((item) => item.status)).toEqual([
      "blocked",
      "unresolved",
    ]);
    expect(workspace.diagnostics).toEqual(
      expect.arrayContaining([
        expect.objectContaining({
          level: "error",
          message: expect.stringContaining("blocked"),
        }),
        expect.objectContaining({
          level: "error",
          message: expect.stringContaining("not supplied"),
        }),
      ]),
    );
  });

  it("refuses executable regex keywords in the bounded validator", () => {
    const workspace = inspectWorkspace([
      {
        name: "pattern.json",
        source: JSON.stringify({ type: "string", pattern: "^(a+)+$" }),
      },
    ]);
    const result = validateJsonInstance(workspace, JSON.stringify("aaaa"));
    expect(result.valid).toBe(false);
    expect(result.diagnostics[0]?.message).toMatch(/pattern.*not executed/iu);
  });

  it("also refuses regex and dynamic-reference keywords in supplied reference documents", () => {
    const regexWorkspace = inspectWorkspace([
      { name: "root.json", source: JSON.stringify({ $ref: "defs.json" }) },
      {
        name: "defs.json",
        source: JSON.stringify({ type: "string", pattern: "^(a+)+$" }),
      },
    ]);
    expect(
      validateJsonInstance(regexWorkspace, JSON.stringify("aaaa")).valid,
    ).toBe(false);
    const dynamicWorkspace = inspectWorkspace([
      {
        name: "dynamic.json",
        source: JSON.stringify({ $dynamicRef: "#node" }),
      },
    ]);
    expect(
      validateJsonInstance(dynamicWorkspace, JSON.stringify({})).diagnostics[0]
        ?.message,
    ).toContain("$dynamicRef");
  });

  it("validates the documented 2020-12 object, array, dependency, and combiner subset", () => {
    const workspace = inspectWorkspace([
      {
        name: "bounded.json",
        source: JSON.stringify({
          $schema: "https://json-schema.org/draft/2020-12/schema",
          type: "object",
          required: ["kind", "values"],
          properties: {
            kind: { enum: ["measurement"] },
            note: { type: "string", minLength: 2, maxLength: 8 },
            values: {
              type: "array",
              prefixItems: [{ type: "integer" }],
              items: { type: "number", minimum: 0 },
              contains: { const: 2 },
              minContains: 1,
              uniqueItems: true,
            },
          },
          dependentRequired: { note: ["kind"] },
          allOf: [{ minProperties: 2 }],
          additionalProperties: false,
        }),
      },
    ]);
    expect(
      validateJsonInstance(
        workspace,
        JSON.stringify({ kind: "measurement", note: "ok", values: [1, 2] }),
      ).valid,
    ).toBe(true);
    const invalid = validateJsonInstance(
      workspace,
      JSON.stringify({ kind: "measurement", values: [1, 1], extra: true }),
    );
    expect(invalid.valid).toBe(false);
    expect(invalid.diagnostics.map((item) => item.message).join("\n")).toMatch(
      /uniqueItems|contains|false schema/u,
    );
  });

  it("supports Draft 6 local files even when root identifiers are remote-looking", () => {
    const workspace = inspectWorkspace([
      {
        name: "root.json",
        source: JSON.stringify({
          $schema: "http://json-schema.org/draft-06/schema#",
          $id: "https://schemas.example.test/root.json",
          $ref: "defs.json#/$defs/value",
        }),
      },
      {
        name: "defs.json",
        source: JSON.stringify({
          $schema: "http://json-schema.org/draft-06/schema#",
          $defs: { value: { type: "integer", minimum: 1 } },
        }),
      },
    ]);
    expect(validateJsonInstance(workspace, "2").valid).toBe(true);
    expect(validateJsonInstance(workspace, "0").valid).toBe(false);
  });

  it("rejects active XML constructs before structural inspection", () => {
    expect(() =>
      parseSchemaDocument({
        name: "unsafe.xsd",
        source: `<!DOCTYPE schema [<!ENTITY x "value">]><schema xmlns="http://www.w3.org/2001/XMLSchema"/>`,
      }),
    ).toThrow(/DTD and entity/u);
  });
});

describe("schema languages", () => {
  it("inventories XSD and generates a clearly heuristic XML instance", () => {
    const workspace = inspectWorkspace([
      {
        name: "person.xsd",
        source: `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:element name="person"><xs:complexType><xs:sequence><xs:element name="name" type="xs:string"/><xs:element name="age" type="xs:integer"/></xs:sequence></xs:complexType></xs:element></xs:schema>`,
      },
    ]);
    expect(workspace.documents.get("person.xsd")?.language).toBe("xsd");
    expect(
      workspace.diagnostics.some((item) =>
        item.message.includes("not provided"),
      ),
    ).toBe(true);
    const sample = generateSample(workspace);
    expect(sample.output).toContain("<person>");
    expect(sample.output).toContain("<name>string</name>");
    expect(sample.notices[0]).toContain("Heuristic XSD");
  });

  it("applies the aggregate text budget to repeated XSD type literals", () => {
    const branches = Array.from(
      { length: 50 },
      (_, index) => `<xs:element name="branch${index}" type="Branch"/>`,
    ).join("");
    const leaves = Array.from(
      { length: 50 },
      (_, index) => `<xs:element name="item${index}" type="LargeText"/>`,
    ).join("");
    const workspace = inspectWorkspace([
      {
        name: "amplified.xsd",
        source: `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:simpleType name="LargeText"><xs:restriction base="xs:string"><xs:enumeration value="${"x".repeat(SCHEMA_LIMITS.sampleValueChars)}"/></xs:restriction></xs:simpleType><xs:complexType name="Branch"><xs:sequence>${leaves}</xs:sequence></xs:complexType><xs:element name="root"><xs:complexType><xs:sequence>${branches}</xs:sequence></xs:complexType></xs:element></xs:schema>`,
      },
    ]);

    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.documentElement.textContent?.length ?? 0).toBeLessThanOrEqual(
      SCHEMA_LIMITS.sampleTextChars,
    );
    expect(parsed.querySelectorAll("*").length).toBeLessThanOrEqual(
      SCHEMA_LIMITS.sampleNodes,
    );
    expect(sample.output.length).toBeLessThanOrEqual(
      SCHEMA_LIMITS.sampleOutputChars,
    );
    expect(sample.notices.join("\n")).toMatch(/text safety bound/iu);
  });

  it("linearly inspects and preindexes a large reused XSD type", () => {
    const leaves = Array.from(
      { length: 20_000 },
      () => `<xs:element name="leaf" type="xs:string"/>`,
    ).join("");
    const branches = Array.from(
      { length: 50 },
      (_, index) => `<xs:element name="branch${index}" type="Heavy"/>`,
    ).join("");
    const source = `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:complexType name="Heavy"><xs:sequence>${leaves}</xs:sequence></xs:complexType><xs:complexType name="Root"><xs:sequence>${branches}</xs:sequence></xs:complexType><xs:element name="root" type="Root"/></xs:schema>`;

    const inspectStarted = performance.now();
    const workspace = inspectWorkspace([{ name: "large-flat.xsd", source }]);
    const inspectElapsed = performance.now() - inspectStarted;
    const generateStarted = performance.now();
    const sample = generateSample(workspace);
    const generateElapsed = performance.now() - generateStarted;
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");

    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.querySelectorAll("*").length).toBeLessThanOrEqual(
      SCHEMA_LIMITS.sampleNodes,
    );
    expect(inspectElapsed).toBeLessThan(2_000);
    expect(generateElapsed).toBeLessThan(2_000);
  });

  it("linearly inspects a wide XSD schema container", () => {
    const annotations = Array.from(
      { length: 20_000 },
      () => "<xs:annotation/>",
    ).join("");
    const source = `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:element name="root"/>${annotations}</xs:schema>`;

    const started = performance.now();
    const workspace = inspectWorkspace([{ name: "wide-root.xsd", source }]);
    const elapsed = performance.now() - started;

    expect(workspace.documents.get(workspace.entry)?.language).toBe("xsd");
    expect(elapsed).toBeLessThan(2_000);
  });

  it("admits exactly 20 generated XSD levels and omits level 21", () => {
    for (const [levels, noticeExpected] of [
      [20, false],
      [21, true],
    ] as const) {
      const workspace = inspectWorkspace([
        { name: `depth-${levels}.xsd`, source: xsdChain(levels) },
      ]);
      const sample = generateSample(workspace);
      const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
      expect(parsed.querySelector("parsererror")).toBeNull();
      expect(parsed.querySelectorAll("*")).toHaveLength(20);
      expect(/level safety bound/iu.test(sample.notices.join("\n"))).toBe(
        noticeExpected,
      );
    }
  });

  it("keeps truncated XSD astral literals well formed", () => {
    const value = `a${"😀".repeat(600)}`;
    const workspace = inspectWorkspace([
      {
        name: "unicode.xsd",
        source: `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:simpleType name="Unicode"><xs:restriction base="xs:string"><xs:enumeration value="${value}"/></xs:restriction></xs:simpleType><xs:element name="root" type="Unicode"/></xs:schema>`,
      },
    ]);
    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(hasUnpairedSurrogate(parsed.documentElement.textContent ?? "")).toBe(
      false,
    );
  });

  it("omits duplicate and fallback-colliding XSD attributes", () => {
    const workspace = inspectWorkspace([
      {
        name: "attributes.xsd",
        source: `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:complexType name="WithAttributes"><xs:attribute name="same"/><xs:attribute name="same"/><xs:attribute name="1bad"/><xs:attribute name="2bad"/></xs:complexType><xs:element name="root" type="WithAttributes"/></xs:schema>`,
      },
    ]);

    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.documentElement.attributes).toHaveLength(2);
    expect(parsed.documentElement.hasAttribute("same")).toBe(true);
    expect(parsed.documentElement.hasAttribute("attribute")).toBe(true);
    expect(sample.notices.join("\n")).toMatch(/duplicate.*attribute/iu);
  });

  it("caches a wide inline XSD type across repeated rendering", () => {
    const annotations = Array.from(
      { length: 20_000 },
      () => "<xs:annotation/>",
    ).join("");
    const branches = Array.from(
      { length: 50 },
      (_, index) => `<xs:element name="branch${index}" type="Branch"/>`,
    ).join("");
    const workspace = inspectWorkspace([
      {
        name: "wide-inline.xsd",
        source: `<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:complexType name="Branch"><xs:sequence><xs:element name="leaf">${annotations}<xs:simpleType><xs:restriction base="xs:string"/></xs:simpleType></xs:element></xs:sequence></xs:complexType><xs:complexType name="Root"><xs:sequence>${branches}</xs:sequence></xs:complexType><xs:element name="root" type="Root"/></xs:schema>`,
      },
    ]);

    const started = performance.now();
    const sample = generateSample(workspace);
    const elapsed = performance.now() - started;
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(elapsed).toBeLessThan(2_000);
  });

  it("inventories Relax NG and Schematron without executing expressions", () => {
    const rng = inspectWorkspace([
      {
        name: "note.rng",
        source: `<grammar xmlns="http://relaxng.org/ns/structure/1.0"><start><element name="note"><element name="body"><text/></element></element></start></grammar>`,
      },
    ]);
    expect(generateSample(rng).output).toContain(
      "<note><body>string</body></note>",
    );
    const sch = inspectWorkspace([
      {
        name: "rules.sch",
        source: `<schema xmlns="http://purl.oclc.org/dsdl/schematron"><pattern id="required"><rule context="person"><assert test="name">A name is required.</assert></rule></pattern></schema>`,
      },
    ]);
    expect(sch.documents.get("rules.sch")?.language).toBe("schematron");
    expect(
      sch.diagnostics.some(
        (item) =>
          item.message.includes("never executed") ||
          item.message.includes("not executed"),
      ),
    ).toBe(true);
  });

  it("retains a direct-root Relax NG element in the generated sample", () => {
    const workspace = inspectWorkspace([
      {
        name: "direct.rng",
        source: `<element xmlns="http://relaxng.org/ns/structure/1.0" name="root"><text/></element>`,
      },
    ]);
    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.documentElement.localName).toBe("root");
    expect(parsed.documentElement.textContent).toBe("string");
  });

  it("never emits more than the exact Relax NG sample node budget", () => {
    const repeatedElements = Array.from(
      { length: SCHEMA_LIMITS.sampleNodes },
      () => `<element name="node"><text/></element>`,
    ).join("");
    const workspace = inspectWorkspace([
      {
        name: "bounded.rng",
        source: `<grammar xmlns="http://relaxng.org/ns/structure/1.0"><start><element name="root"><group>${repeatedElements}</group></element></start></grammar>`,
      },
    ]);

    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.querySelectorAll("*")).toHaveLength(
      SCHEMA_LIMITS.sampleNodes,
    );
  });

  it("applies the aggregate text budget through repeated Relax NG refs", () => {
    const references = Array.from(
      { length: SCHEMA_LIMITS.sampleNodes },
      () => `<ref name="large"/>`,
    ).join("");
    const workspace = inspectWorkspace([
      {
        name: "text-budget.rng",
        source: `<grammar xmlns="http://relaxng.org/ns/structure/1.0"><define name="large"><value>${"x".repeat(SCHEMA_LIMITS.sampleValueChars)}</value></define><start><element name="root"><group>${references}</group></element></start></grammar>`,
      },
    ]);

    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.documentElement.textContent?.length ?? 0).toBeLessThanOrEqual(
      SCHEMA_LIMITS.sampleTextChars,
    );
    expect(sample.notices.join("\n")).toMatch(/text safety bound/iu);
  });

  it("bounds amplified Relax NG pattern visits independently of output", () => {
    const width = 300;
    const emptyPatterns = Array.from({ length: width }, () => "<empty/>").join(
      "",
    );
    const references = Array.from(
      { length: width },
      () => `<ref name="fanout"/>`,
    ).join("");
    const workspace = inspectWorkspace([
      {
        name: "amplified-work.rng",
        source: `<grammar xmlns="http://relaxng.org/ns/structure/1.0"><define name="fanout"><group>${emptyPatterns}</group></define><start><element name="root"><group>${references}</group></element></start></grammar>`,
      },
    ]);

    const started = performance.now();
    const error = captureError(() => generateSample(workspace));
    const elapsed = performance.now() - started;
    expect(error.message).toMatch(/sample budget was exhausted/iu);
    expect(elapsed).toBeLessThan(2_000);
  });

  it("caches wide reused Relax NG pattern containers", () => {
    const ignored = Array.from({ length: 19_000 }, () => "<empty/>").join("");
    const references = Array.from(
      { length: 1_000 },
      () => '<ref name="wide"/>',
    ).join("");
    const workspace = inspectWorkspace([
      {
        name: "wide-reused.rng",
        source: `<grammar xmlns="http://relaxng.org/ns/structure/1.0"><define name="wide"><choice><empty/></choice>${ignored}</define><start><element name="root"><group>${references}</group></element></start></grammar>`,
      },
    ]);

    const started = performance.now();
    const sample = generateSample(workspace);
    const elapsed = performance.now() - started;
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.documentElement.localName).toBe("root");
    expect(elapsed).toBeLessThan(2_000);
  });

  it("counts generated Relax NG levels rather than wrapper patterns", () => {
    for (const [levels, noticeExpected] of [
      [20, false],
      [21, true],
    ] as const) {
      const workspace = inspectWorkspace([
        { name: `depth-${levels}.rng`, source: relaxNgChain(levels) },
      ]);
      const sample = generateSample(workspace);
      const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
      expect(parsed.querySelector("parsererror")).toBeNull();
      expect(parsed.querySelectorAll("*")).toHaveLength(20);
      expect(/level safety bound/iu.test(sample.notices.join("\n"))).toBe(
        noticeExpected,
      );
    }
  });

  it("keeps truncated Relax NG astral literals well formed", () => {
    const value = `a${"😀".repeat(600)}`;
    const workspace = inspectWorkspace([
      {
        name: "unicode.rng",
        source: `<element xmlns="http://relaxng.org/ns/structure/1.0" name="root"><value>${value}</value></element>`,
      },
    ]);
    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(hasUnpairedSurrogate(parsed.documentElement.textContent ?? "")).toBe(
      false,
    );
  });

  it("omits duplicate and fallback-colliding Relax NG attributes", () => {
    const workspace = inspectWorkspace([
      {
        name: "attributes.rng",
        source: `<element xmlns="http://relaxng.org/ns/structure/1.0" name="root"><attribute name="same"/><attribute name="same"/><attribute name="1bad"/><attribute name="2bad"/><text/></element>`,
      },
    ]);

    const sample = generateSample(workspace);
    const parsed = new DOMParser().parseFromString(sample.output, "text/xml");
    expect(parsed.querySelector("parsererror")).toBeNull();
    expect(parsed.documentElement.attributes).toHaveLength(2);
    expect(parsed.documentElement.hasAttribute("same")).toBe(true);
    expect(parsed.documentElement.hasAttribute("attribute")).toBe(true);
    expect(sample.notices.join("\n")).toMatch(/duplicate.*attribute/iu);
  });

  it("parses OpenAPI YAML, inventories operations, and derives component samples", () => {
    const workspace = inspectWorkspace([
      {
        name: "openapi.yaml",
        source: `openapi: 3.1.0
info:
  title: Local API
  version: 1.0.0
paths:
  /people:
    get:
      responses:
        "200": { description: ok }
components:
  schemas:
    Person:
      type: object
      required: [name]
      properties:
        name: { type: string }
`,
      },
    ]);
    const document = workspace.documents.get("openapi.yaml")!;
    expect(document.language).toBe("openapi");
    expect(document.summary).toContainEqual({
      label: "Operations",
      value: "1",
    });
    expect(JSON.parse(generateSample(workspace).output)).toEqual({
      name: "string",
    });
  });

  it("refuses an impossible OpenAPI component sample", () => {
    const workspace = inspectWorkspace([
      {
        name: "impossible-openapi.json",
        source: JSON.stringify({
          openapi: "3.1.0",
          info: { title: "Impossible", version: "1" },
          paths: {},
          components: { schemas: { Impossible: false } },
        }),
      },
    ]);
    expect(() => generateSample(workspace)).toThrow(/no valid sample/iu);
  });

  it("applies the same 20-level depth ceiling to OpenAPI samples", () => {
    const workspace = inspectWorkspace([
      {
        name: "deep-openapi.json",
        source: JSON.stringify({
          openapi: "3.1.0",
          info: { title: "Deep", version: "1" },
          paths: {},
          components: { schemas: { Deep: nestedJsonSchema(21) } },
        }),
      },
    ]);
    const sample = generateSample(workspace);
    expect(jsonValueDepth(JSON.parse(sample.output))).toBe(20);
    expect(sample.notices.join("\n")).toMatch(/level safety bound/iu);
  });
});

describe("conservative comparison", () => {
  it("signals newly required fields and removed enum values", () => {
    const changes = compareSchemas(
      {
        name: "before.json",
        source: JSON.stringify({
          type: "object",
          properties: { state: { enum: ["on", "off"] } },
        }),
      },
      {
        name: "after.json",
        source: JSON.stringify({
          type: "object",
          required: ["state"],
          properties: { state: { enum: ["on"] } },
        }),
      },
    );
    expect(changes).toEqual(
      expect.arrayContaining([
        expect.objectContaining({
          level: "incompatible",
          message: expect.stringContaining("required"),
        }),
        expect.objectContaining({
          level: "incompatible",
          path: "/properties/state/enum",
          message: expect.stringContaining("removed"),
        }),
      ]),
    );
  });

  it("signals removed OpenAPI operations", () => {
    const base = {
      openapi: "3.1.0",
      info: { title: "Example", version: "1" },
    };
    const changes = compareSchemas(
      {
        name: "before.json",
        source: JSON.stringify({
          ...base,
          paths: {
            "/items": { get: { responses: { "200": { description: "ok" } } } },
          },
        }),
      },
      { name: "after.json", source: JSON.stringify({ ...base, paths: {} }) },
    );
    expect(changes).toContainEqual(
      expect.objectContaining({ level: "incompatible", path: "GET /items" }),
    );
  });
});